One of our major objectives involves the study of membranes of the epithelial cell of the small intestine using techniques developed in our laboratory which permit the isolation and separation of microvillus and vasolateral membranes. We will examine the factors influencing the transport of nutrients, especially sugar and amino acids by membrane vesicles. We will also study the differences in uptake and translocation by the membranes from mature differentiated villus cells compared to undifferentiated crypt cells. Changes in membrane function in absorptive disorders such as gluten-induced enteropathy (sprue) will be investigated. BIBLIOGRAPHIC REFERENCES: Warshaw, A.L., Walker, W.A. and Isselbacher, K.J. Protein uptake by the intestine: Evidence for absorption of intact macromolecules. Gastroenterology 66:987, 1974. Perrotto, J.L., Hang, L., Isselbacher, K.J. and Warren, K.S. Systemic cellular hypersensitivity induced by an intestinally absorbed antigen. J. Exp. Med. 140:296, 1974.